PURPOSE: To automatically control the density of a copying machine easily and speedily with high precision, by reading the density of toner stuck as a trial to a photosensitive drum before copying operation, and controlling a development bias voltage and the amount of toner to be applied.
CONSTITUTION: Prior to copying operation, the surface of a photosensitive drum 8 is charged to have residual charges uniformly with the quantity of light attenuated through an exposure attenuator 2 inserted into an optical path, and under the control of a residual charge erasing lamp 4 formed of plural LEDs over the drum width a toner is stuck to a specified small area part of the drum 8 as a trial. The density of the toner is detected by a density sensor 11 and compared with a reference value by an operational amplifier 12 to automatically control the most effective rotation of a toner supplying motor 5 for density control and the bias voltage of a development bias voltage generator 7' with the fastest response through a CPU15. Thus, the density of the copying machine is controlled automatically, easily, and speedily with high precision.
YASUI HIROKAZU
HIRAYAMA YOSHIFUMI
MATSUURA AKIRA
| JPS54134646A | 1979-10-19 |
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